This application requests travel support for United States scientists planning to participate in the 25th Annual Meeting of the International Narcotic Research Conference (INRC). This conference will take place July 16-21, 1994 at Sea Crest in North Falmouth, Cape Cod, Massachusetts. It is being organized by Dr. Eric Simon, the Program Chair, heading a Local Organizing Committee. Input is provided by the INRC Secretary (the Co-PI, H. Akil) and the INRC Executive Committee, which oversees program balance within and across annual conferences. This conference has been tentatively approved as a satellite of the International Pharmacology Meeting (IUPHAR) in Montreal. The 1994 INRC meeting promises to be particularly exciting. The cloning of the first opioid receptor (delta type) in late 1992 has opened the door for the identification and characterization of other opioid receptor types and subtypes. Several laboratories have been vigorously pursuing research in this area. Kappa receptors have been cloned in several species by multiple labs, and preliminary evidence of their heterogeneity has already emerged. Parallel investigations of delta heterogeneity are underway. To our knowledge, a member of the mu receptor family has not been fully identified yet, but this will likely change in the foreseeable future. Thus, the 1994 Meeting will represent the first INRC meeting where the issue of receptor heterogeneity can be fully reexamined in light of molecular biological data. It will be critical to evaluate the structural, pharmacological, physiological, behavioral and clinical implications of these findings. In many ways, the recent developments will help re-chart the course of research in several areas of this field. Furthermore, there are a number of new concepts, breakthroughs and novel research strategies being used in other areas of opioid research, ranging from the molecular biology of opioid peptide gene expression, to novel views of opiate tolerance and dependence, to new concepts regarding the motivational aspects of opioid systems. The INRC meeting is an ideal vehicle to ensure that these ideas will be thoroughly evaluated and discussed, and that young scientists will participate in these discussions. Travel funds will be dispersed according to a well defined hierarchy of priorities, with junior scientists being given first preference. A portion of the grant will be earmarked for supporting scientific symposia at the meeting, and a small amount will be used for administration and disbursement of travel funds and in support of publication of the proceedings.